A typical circuit board assembly includes a circuit board formed of circuit board materials (e.g., fiberglass, copper, etc.) and circuit board components mounted to the circuit board. Examples of circuit board components include integrated circuits (ICs), resistors, and inductors. Certain conventional ICs, such as ball grid array (BGA) devices, have an array of solder balls (e.g., solder columns) that attach to contact pads, for example, located on the circuit board. The array of solder balls provides mechanical attachment of the BGA device to the circuit board (e.g., attachment to the contact pads of the circuit board) and provides electrical contact between the BGA device and the circuit board.
Conventionally, circuit board components generate heat during operation. A fan assembly typically generates an air stream that passes over the components and carries the heat away from the circuit board components. The air stream removes the heat so that the components do not operate in an unsafe temperature range, i.e., a relatively high temperature range that would cause the components to operate improperly (e.g., generate a signal incorrectly) or sustain damage (e.g., overheat, burnout, etc.).
Some ICs utilize heat sinks to facilitate cooling. In general, a heat sink is a flanged thermally conductive device, such as a metallic device, that contacts a package of the IC. As the IC generates heat, heat flows from the IC package to the heat sink, and dissipates into the surrounding air. The air stream generated by the fan assembly then carries the heat away, thereby cooling the IC.
As the power requirements for ICs increase, the amount of heat generated by relatively high powered ICs also increases. In turn, the relatively high-powered ICs require larger heat sinks having larger surface areas for heat transfer and heat dissipation of the heat created by the ICs.
Conventional circuit board assemblies use a variety of techniques to secure heat sinks to corresponding circuit board components or ICs in order to maintain thermal contact between the heat sinks and IC packages during operation. One such technique involves the use of a double-sided thermally conductive adhesive, also known as a Pressure Sensitive Adhesive (PSA), to secure the heat sink to the IC package. The PSA contacts a base plate of the heat sink and a surface of the IC package to couple the heat sink and IC package and maintain thermal contact between the heat sink and the IC package and to secure the heat sink to the IC package. Another conventional technique involves the use of fasteners and bolster plates to secure the heat sink to the IC package using the IC's circuit board. Each fastener engages a mounting hole on the heat sink, a mounting hole or through hole defined by the circuit board, and a bolster plate located on a surface of the circuit board component opposite to the surface carrying the IC package. As each fastener engages the corresponding bolster plate, each fastener causes the heat sink to generate a load on the IC package to ensure thermal contact between the heat sink and the IC package.
Another conventional technique involves the use of fasteners and springs to secure the heat sink to the IC package using the IC's circuit board. Each fastener engages a mounting hole on the heat sink, a corresponding spring, and a mounting hole or through hole defined by the circuit board. Each fastener compresses a corresponding spring and causes the heat sink to generate a load on the IC package to ensure thermal contact between the heat sink and the IC package. In such a configuration the springs adjust or absorb a portion of the load exerted by the fasteners on the IC package. Another conventional technique involves the use of spring clips to secure the heat sink to the IC package and maintain thermal contact between the heat sink and IC package. The spring clips contact the heat sink and secure the heat sink to the IC package by attaching directly into openings defined by the circuit board in the area of the IC package.